Internal combustion engine



y 21, 957 w. H. SMITH 2,792,817

INTERNAL COMBUSTION ENGINE Filed Nov. 29, 1955 INVENTOR.

ATTORNEY m in United States Patent'O INTERNAL COMBUSTION ENGINE WarrenH. Smith, Detroit, Mich., assignor to General Motors Corporation,Detroit, Mich., a corporation of Delaware Application November 29, 1955,Serial No. 549,745

5 Claims. (Cl. 123-65) This invention relates to an internal combustionengine and more particularly to such an engine adapted to burn a gaseousfuel.

Among the principal objects of the invention is to provide such anengine with means including an improved combustion chamber adapted toimprove the firing regularity in the individual engine cylinders, reducethe general noise characteristics of the engine, improve thefuel economyof the engine, and permit the use of higher compression ratios.

The combined means for accomplishing the foregoing and other objects andadvantages of the invention will be more thoroughly understood from thefollowing description of a preferred embodiment thereof in whichreference is made to the attached drawing, in which:

Figure 1 is a longitudinal sectional view of an engine cylinderembodying the invention; and

Figure 2 is a sectional view of the head portion of the engine cylindertaken substantially on the line 2-2 of Figure 1.

Referring more particularly to the drawing, Figure 1 shows a cylinderassembly for a loop-scavenged, twocycle, internal combustion gas engine.The cylinder assembly includes a cylinder block having a sleeve-linedbore 12 therein reciprocably mounting a piston 14. The bore 12 is closedat its upper end by a cylinder head 16 which may be formed integrally ofthe block, as shown, or may be several of the block and suitably securedthereto. Intermediate its ends, the cylinder block and the cylinderliner are provided with a plurality of aligned air inlet passages 18 andports 20, respectively," and with a plurality of aligned exhaustpassages 22 and ports 24, respectively. As is conventional in suchtwo-cycle, loopscavenged engines, the inlet and exhaust ports arecontrollatble by the piston and subtend arcs on opposite sides of thecylinder. The exhaust ports 22 .are' of greater longitudinal dimensionthat the inlet ports 20 and, consequently, are opened earlier by thedownward movement of the piston and are closed laterby the upwardmovement of the piston than the inlet ports. The inlet passages 18, theports 20, and the crown of the piston are formed so as to cause thescavenging and charging inlet air to travel upwardly adjacent the inletside of the cylinder toward the cylinder head and across the cylinderhead thereby forcing the exhaust gases downwardly on the exhaust side ofthe cylinder and out through the exhaust ports as indicated by thearrows a in Figure 1. As the inlet ports and subsequently the exhaustports are closed by the upward compression stroke of the piston, themovement of air thus initiated in the cylinder when the ports are openresults in a clockwise vortical circulation of the entrapped air chargewithin the cylinder as viewed in Figure 1.

As the piston 14 approaches its uppermost position as shown in Figure 2,the crown of the piston and the coacting surfaces of the cylinder head16 define a combustion chamber 26 therebetween. In the illustrative em-2,792,817 Patented May 21, 1957 bodiment of the invention, the opposedsurfaces of the head and piston crown'include coacting frusto-conicalouter surface portions 28 and 30, respectively. The piston crown is alsoprovided with a central bowl 32 of the open or semi-turbulent type whilethe central portion of the cylinder'head is substantially flat exceptfor a semi-discal groove 34 opening on said chamber and extendingtransversely thereof from the inlet side to the outlet side of thecylinder. A gaseous fuel inlet passage 36 in the cylinder headterminates in a port 38 opening on the groove 34 adjacent the inlet sideof the cylinder, and a poppet valve 40" associated with the port 38 isadapted to control the sequential admission of fuel into the cylinder.While two spark plug's'42are shown mounted in the head, thespark-gapjends of which project into the groove 34, in transverselyspaced relation to the poppet valve, any suitable ignition-initiatingdevice such as a pilot fuel oilinjector or glow plug'might besubstitutedtherefor, and it is not essential to the practice of the invention thatmore than one ignition device be utilized.

In high-compression gas engines of this type, it is essential that theair charge supplied to the individual cylinders be in excess of thatrequired to support the complete com-bustion of the gaseous charge andthat the ignition timing or firing regularity within the severalcylinders is properly controlled so that the power generated by thecombustion .of the gaseous charge is smoothly applied to the piston'andconsequentially to the associated parts of the engine. However, if therequired excessive air charge were completely mixed with the gaseouscharge, a relatively lean power or noncombustible mixture would result.Hence, it is necessary that the gaseous charge within such enginecylinders be presented to the ignition device in a relatively richmixture, with subsequent mixing of the gaseous and air charges occurringas a result of the initial combustion process.

In the embodiment of the invention herein described, as the piston 14approaches its uppermost position, a portion of the vorticallycirculating air charge is enrapped between the coacting frusto-conicalsurface portions of the head and piston crown and, consequentially, isforced r-adially inwardly of the combustion chamber. This inwardmovement of this portion of the air charge tends to set up toroidal airflow between the cylinder head and the bowl of the piston crown asindicated by the arrows b in Figure 2. However, this toroidal air flowis broken into two semi-toroids disposed on opposite sides of the pistonby a trough of air which continues to circulate vortically within thegroove 34 and a diametrical portion of the piston bowl as indicated bythe arrows c. At a predetermined point in the operating cycle for theparticular engine cylinder, generally as the piston approaches itsuppermost position, the poppet valve 40 is caused to open admitting agaseous fuel charge into the cylinder. In accordance with the invention,the vortical flow of the air charge confined within the groove 34 andthe aforementioned diametrical portion of the piston bowl carries astratum of relatively rich combustible mixture from the port 38 to thezone where the igniting device is effective to initiate combustion.Since the velocities of the vortically circulating air will be afunction of the speed of the engine, a definite time relationshiprelative to the operative position of the piston can be establishedbetween the opening of the valve 40 and the time that the combustiblemixture reaches the effective zone of the igniting device. Consequently,firing within each cylinder may be carefully regulated to achieve arelatively smooth propagation of the combustion flame front as theremaining gaseous charge is mixed with the remaining air charge by theturbulence induced by the initial combustion. In this manner, thecombustion-generated power is applied 3 relatively smoothly tothepi'stons and associated parts of the engine thereby increasing theoperative life of "such parts and reducing the noise level of theengine.

It will thus be seen that the several objects and advantageous resultsof the invention are achieved in the illustrative embodiment of theinvention. While only one preferred embodiment of the invention has beenshown and described, it will be appreciated by .those skilled in the artthat various modifications maybe made therein without departing from thespirit and scope of the invention as defined in the following claims.

I claim:

1. In an internal combustion engine, a cylinder having a head closingone end, a piston reciprocably mounted in said cylinder, said head andsaid piston defining a combustion chamber therebetween, means associatedwith said cylinder for introducing .an air charge therein .and forinducing a vortical circulation of the air charge causing the air tomove toward said head adjacent one .side of the cylinder and away fromsaid head adjacent the diametrically opposite side of the cylinder, saidhead having a groove therein opening on and extending diametrically ofsaid cylinder from said one side to said opposite side, means forsequentially introducing gaseous fuel into said groove adjacent said oneside, and means transversely spaced of said last-mentionedmeans withinsaid groove for initiating combustion of a combustible mixture of saidfuel and said air carried thereto by the vortical flow of said air.

2. In an internal combustion engine, means defining an expansiblecombustion chamber including a cylinder element closed at one end and apiston element mounted therein, said cylinder element :and 'said pistonelement being reciprocable relative to each other, means associated withatleast one of said elements for introducing an air charge into saidexpansible chamber and for inducing vortical flow of said air .chargetherein, a groove in at least one of said elements opening on saidcombustion chamber and extending in the direction of 'said'vorticalflow, means for introducing a gaseous fuel into said groove, andignition-initiating means :in said groove spaced from said fuel-inducingmeans whereby a stratum of combustible mixture of said fuel and said airis carried to said ignition-initiating means by the vortical flow of airwithin the expansible chamber.

3. In a two-cycle gas engine, the combination including a cylinderhaving a head closing one end thereof, a piston reciprocably mounte'dinsaid cylinder, the opposed surface portions of said piston and saidhea'ddefining a combustion chamber therebetween, saidhea'd having asemidiscal groove opening on said combustion chamberrand extendingtransversely of said cylinder, valve means for introducing gaseous 'fuelinto one end of said groove, an ignition-initiating device spacedtransversely of said cylinder from said'valve means within said groove,said cylinder having a plurality of air inlet and exhaust portsintermediate its ends controllable by the piston, said ports andsaid'piston being formed to 'eausethe 'scavenging'and charging inlet airto travel upwardly in a column adjacent said one side of the cylindertoward said head thereby inducing a vortical flow of the charging airwithin the cylinder, said vortical flow being adapted to carry a stratumof relatively rich combustible mixture of said fuel and said air fromsaid valve means to said ignition-inducing device Within said groove.

4. In a loop-scavenged, two-cycleigas engine, the'combination includinga cylinder having a'headlclosing one end thereof, a piston reciproca-blymounted insaid cylinder, said cylinder having a plurality of air inletand exhaust ports intermediate its ends and controllable by said piston,said ports and said piston'being formed so as to cause the scavengingand charging inlet air to travel upwardly in a column adjacent one sideof the cylinder toward said head thereby inducing vortical flow of thecharging air within the cylinder, the opposed surface portions of saidpiston and said closed end defining a combustion chamber therebetweenincluding coating frustoconical outer surface portions, said pistonhaving a bowl therein centrally of the frusto-conical outer surfaceportion, said head haw'ng a semi-discal groove opening on saidcombustion chamber and extending transversely of said cylinder, valvemeans for introducing gaseous fuel into one end of said groove and anignition-initiating deviced spaced transversely of said cylinder fromsaid valve means within said groove, the outer surface portions of saidpiston and said closed end forcing air entrapped therebetween during thecompression stroke of said piston into said central chamber with atoroidal motion, and said vortical flow being adapted to carry a stratumof relatively rich combustible mixture of said fuel and said air fromsaid valve means to said ignition-inducing device within said groove.

5. In an engine, means defining an expansible combustion chamberincluding a cylinder element .closed at one end and a piston elementmounted therein, said cylinder element and said piston element beingreciprocable relative to each other, a groove in at least one of saidelements opening on said combustion chamber, means for introducing agaseous fuel into said groove, ignitioninitiating means in saidgroovespaced from said fuel-inducting means, and means associated with atleast one of said elements for introducing an air charge into saidexpansible chamber and inducing vortical .flow within said chamberwhereby a stratum of combustible mixture of said .fuel and said air iscarried directly from said fuelintroducing means tosaidignition-initiating means within said groove.

References Cited in the file :of this :patent UNITED STATES PATENTS2,391,176 .Mallory Dec. 18, 1945

